Graduates from Columbia University's School of Journalism cheer during the university's commencement ceremony in New York in this file photo. For academic fields whose members revere a 'spark of genius' above all other qualities, there is a disquieting message at US colleges and universities: women need not apply. That's the findings of new research.

As the country strives to improve education in science, technology, engineering, and math, one issue that continues to dog the effort is a relative dearth of women in some key STEM fields at the nation's universities.

One possible reason for the gap: The belief among many faculty, graduate students, and newly minted PhDs who have yet to nail down a faculty position that to succeed in fields such as physics or computer science, hard work and persistence alone won't cut it. A person needs something, which Princeton University philosopher Sarah-Jane Leslie terms "a special unteachable spark of brilliance" that society does not tend to associate with women.

That's the essence of a study Dr. Leslie and colleagues are publishing in Friday's issue of the journal Science. The work sought to test the notion that society tends to associate unteachable brilliance with males and sees such brilliance as indispensable for success in some disciplines, sending otherwise qualified female students into other fields.

Widespread cultural influence, from TV's "Sherlock" to J.K. Rowling's "Harry Potter" series, tends "to link men, but not women, with raw intellectual brilliance," Leslie says. The lead females in these tales are smart, but their achievements are based on hard work rather than innate brilliance.

The team found a strong relationship between a belief that specific fields demanded the spark of brilliance and the number of female PhDs in that field. The more intense the belief among grad students, post docs, and faculty that unteachable brilliance was needed, the fewer the women holding PhDs in that field. The relationship was just as strong for physics, where women earn less than 20 percent of PhDs as it was for music composition.

With so much focus placed on women's representation in college-level STEM education, "people assume that women are well represented in social sciences and humanities disciplines, but the reality is much more complex than that," Leslie says.

The study grew out of a conversation Leslie had with Andrei Cimpian, a psychologist at the University of Illinois at Urbana-Champaign during a science conference. Comparing notes about the demands of their respective fields, she noted that philosophers tend to place a lot of emphasis on raw brilliance as the key to success in a field where women hold about 35 percent of the PhDs. In psychology, the emphasis in on hard work, with women holding roughly 75 percent of the PhDs. That led them to wonder how widespread the patterns might be.

The researchers tapped two other colleagues, including the associate director of the Princeton Survey Research Center, and design a questionnaire the team sent to professors, post docs, and graduate students associated with 12 STEM disciplines, as well as nine social-science and nine humanities disciplines. The researchers contacted more than 28,000 people and received 1,280 useable responses.

The team's survey also tested three other possible reasons researchers have offered for the low proportion of women PhDs in fields where they are deemed underrepresented:

The suggestion that women tend to be unwilling or unable to put in the long hours into earning a PhD in fields that require long hours in order to succeed.

The suggestion that men and women just have different interests and aptitudes that inform their decision on which discipline to pursue, with men following paths that require a great deal of systematic, abstract thinking, while women tend toward paths that require empathy and emotional understanding.

The suggestion that the two sexes display intellectual differences that tend to favor males when each considers attaining an advanced degree in disciplines considered more intellectually demanding and elite than others.

"When we looked at the data, we saw that none of these three hypotheses was able to predict the pattern of female representation across the entire set of 30 disciplines," says Dr. Cimpian.

The researchers acknowledge that this was an initial test. It looked only at the potential relationship between a perceived demand for innate brilliance and a field's distribution of women with doctorates. The next round of work will try to pinpoint reasons why those beliefs pare down the proportion of women holding PhDs in those fields.

For now, however, the data suggest that emphasizing persistence and hard work over "brilliance" or "genius" could start to boost women's representation, the team suggests.

The findings are intriguing, writes Andrew Penner, a sociologist at the University of California at Irvine in an essay in Science accompanying the study. In explaining why more women are involved in some STEM fields than others, it avoids some of the pitfalls that accompany other explanations for the gender gaps.

But he also points to powerful figures such as German Chancellor Angela Merkel, who has a degree in physical chemistry, and the late Margaret Thatcher, who began her career as a research chemist.

Even as efforts continue to boost the representation of women in STEM careers at universities, society should beware of "trivializing" the choices men and women make to earn science degrees then take their talents into the wider world.